Development of a 3D ordered macroporous RuO2 electrode for efficient pyrazole removal from water

Inability to remove biologically toxic and persistent contaminants is a critical issue in traditional water treatment processes. In this study, a novel 3D macroporous RuO2 (3D-RuO2) electrode with uniform and interconnected cavities has been fabricated via templated electrodeposition approach for treatment of persistent pyrazole. The physicochemical properties of the electrodes are characterized by means of SEM, BET, XRD, LSV and CV measurements. The results show that structural features of the 3D-RuO2 play important roles in the electrocatalysis performance. Thanks to the abundant crystal defect sites, 3D-RuO2 electrode possesses more mesopores within the skeleton, resulting in 17.9 and 2.2 times larger specific surface area compared to traditional flat thermal-deposited (TF-RuO2) and electrodeposited RuO2 (EFRuO2) respectively. At a current density of 5 mA cm(-2) , the pyrazole removal rate on 3D-RuO2 is 1.7 times and 1.3 times that of TF-RuO2 and EF-RuO2. The energy consumption for 50% of pyrazole removal on 3DRuO(2) is 0.05 kWh g(-1) pyrazole, much lower than that of TF-RuO2 (0.11 kWh g(-1) pyrazole) and EF-RuO2 (0.075 kWh g(-1) pyrazole). The improved removal performance of 3D-RuO2 electrode is attributed to its strong electro-adsorption capacity (270.3 mu g cm(-2)), leading to enhanced mass transfer of pollutants to the electrode surface. The mass transfer coefficient (kappa(m)) is estimated as 2.4 x 10(-6) m s(-1) for 3D-RuO2, which is 3.9 and 23 times as much as that of TF-RuO2 and EF-RuO2. Finally, contribution of different electron transfer approaches to pyrazole degradation under anodic polarization was investigated by ROS scavenging experiments. (C) 2019 Published by Elsevier Ltd.